1 The role of alarm systems in conscious experience has been particularly highlighted by Kevin O’Regan’s concept of the ‘grabbiness’ of perception – that is, if something changes in the image, it grabs your attention. J. K. O’Regan, Why Red Doesn’t Sound Like a Bell: Understanding the Feel of Consciousness (Oxford: Oxford University Press, 2011).
2 Redrawn with permission from A. Mack and I. Rock (1999), ‘Inattentional blindness’, Psyche, 5(3): Figure 2.
3 J. S. Macdonald and N. Lavie (2011), ‘Visual perceptual load induces inattentional deafness’, Attention, Perception, & Psychophysics, 73(6): 1780–89.
4 Redrawn with permission from Mack and Rock (1999), ‘Inattentional blindness’, Figure 3.
5 Inattentional blindness and deafness require going ‘under the radar’ of the alarm system – a bright flash or a loud bang would surely be detected, however carefully we are focusing on the central cross, because the alerting mechanisms will drag our focus from the cross to the unexpected, rather shocking, stimulus. But this is not a case of locking onto two set of information – the shock of the flash (or, equally, a loud bang) would disengage our existing visual analysis of the arms of the cross and, we would presume, dramatically reduce the accuracy of our judgements concerning which arm is longer.
6 Reprinted with permission from R. F. Haines (1991), ‘A breakdown in simultaneous information processing’, in Presbyopia Research, ed. G. Obrecht and L. W. Stark (Boston, MA: Springer), pp. 171–5.
7 U. Neisser, ‘The control of information pickup in selective looking’, in A. D. Pick (ed.), Perception and its Development: A Tribute to Eleanor J. Gibson (Hillsdale, NJ: Lawrence Erlbaum Associates, 1979), pp. 201–19.
8 A wonderful update of this study, where the woman with the umbrella is replaced by a person in a gorilla suit, became something of a YouTube hit. D. J. Simons and C.F. Chabris (1999), ‘Gorillas in our midst: Sustained inattentional blindness for dynamic events’, Perception, 28(9): 1059–74.
9 The possibility that many objects, faces and words are analysed at a ‘deep’ level, but only one or so is then selected by attentional resources is the ‘late-selection’ theory of attention (J. Deutsch and D. Deutsch (1963), ‘Attention: Some theoretical considerations’, Psychological Review, 70(1): 80).
10 This does not mean that the brain processes only pieces of information relevant to the object, word, face or pattern that is the current focus of attention. Indeed, some amount of processing of irrelevant information is inevitable, because the brain can’t always know which new pieces of information are part of the current ‘jigsaw’. This point is demonstrated elegantly in experiments in which people listen to different voices ‘speaking’ into left and right headphones. Instructed to listen to, and immediately repeat, the voice in the left ear, people have almost no idea what the other voice is saying (D. E. Broadbent, Perception and Communication (Oxford: Oxford University Press, 1958); N. P. Moray (1959), ‘Attention in dichotic listening: Affective cues and the influence of instructions’, Quarterly Journal of Experimental Psychology, 11: 56–60). For example, they can fail to notice that the unattended voice is speaking in a foreign language or repeating a single word. But suppose the messages abruptly switch ears – so that the natural continuation of the sentence heard in the left ear now continues in the right ear (A. Treisman (1960), ‘Contextual cues in selective listening’, Quarterly Journal of Experimental Psychology, 12: 242–8). In this case people frequently ‘follow’ the switched message to the other ear. As the brain is continually searching for new ‘data’ that matches as well as possible with its existing ‘jigsaw’, when new ‘jigsaw pieces’ appear to fit unexpectedly well with the current jigsaw, the brain ‘grabs’ hold of them. Yet the cycle of thought is rigidly sequential: we can only fit new information into one mental jigsaw at a time.
11 Of course, the brain has to figure out which pieces of information are meaningfully grouped together. Even if we are solving one jigsaw at a time, we may need to make some sense of other irrelevant jigsaw pieces in order to reject them – for example, if we are working on a jigsaw containing a rural scene, spotting that a jigsaw piece or pieces that make up a fragment of aircraft engine might lead us to put them aside. In the same way, the brain imposes meaning on information irrelevant to the meaningful pattern it is constructing just enough to reject it as irrelevant.
12 Indeed, the most popular model of how eye movements and reading work, the E–Z Reader model, assumes that attention shifts completely sequentially, from one word to the next, with no overlaps – even though there would seem to be huge advantages to being able to read many words simultaneously. Attention locks on and makes sense of one word after the next, exemplifying the cycle of thought viewpoint (see, for example, E. D. Reichle, K. Rayner and A. Pollatsek (2003), ‘The E–Z Reader model of eye-movement control in reading: Comparisons to other models’, Behavioral and Brain Sciences, 26 (4): 445–76.
13 G. Rees, C. Russell, C. D. Frith and J. Driver (1999), ‘Inattentional blindness versus inattentional amnesia for fixated but ignored words’, Science, 286(5449): 2504–507.
14 Some primitive aspects of the perceptual world may, though, be grasped without the need for attention. Indeed, such processing seems to be a prerequisite for attentional processes to be able to select and lock onto specific aspects of aspects of the visual input or stream of sounds. We shall not consider here the vexed question of what information the brain can extract without engaging the cycle of thought – but note that it will not include describing the world as consisting of ‘meaningful’ items such as words, faces or objects, but rather will be closely tied to features of the sensory input itself (e.g. detecting bright patches, textures, or edges – although none of these is uncontroversially pre-attentive). See, for example, L. G. Appelbaum and A. M. Norcia (2009), ‘Attentive and pre-attentive aspects of figural processing’, Journal of Vision, 9(11): 1–12; Li, Zhaoping (2000), ‘Pre-attentive segmentation in the primary visual cortex’, Spatial Vision, 13 (1): 25–50.
15 D. A. Allport, B. Antonis and P. Reynolds (1972), ‘On the division of attention: A disproof of the single channel hypothesis’, Quarterly Journal of Experimental Psychology, 24(2): 225–35.
16 L. H. Shaffer (1972), ‘Limits of Human Attention’, New Scientist, 9 November: 340–41; L. H. Shaffer, ‘Multiple attention in continuous verbal tasks’, in P. M. A. Rabbitt and S. Domic (eds), Attention and Performance V (London: Academic Press, 1975).